Capturing Carbon Dioxide from the Air

One researcher argues it might be cheaper than offsetting coal emissions with solar power.

October 2, 2009

One
way to counteract the rise in greenhouse gases in the atmosphere is to make use
of known chemical reactions to capture carbon dioxide from the atmosphere and store
it underground or use it to make something useful like hydrocarbon fuels or
plastics. The process is similar to what plants do as they convert carbon
dioxide into roots and leaves, but using industrial processes might make it happen
faster and on a larger scale.

The
question is whether this can be done cheaply enough to be worthwhile. Some
have argued that the existing processes are too expensive, and that what’s
needed is basic research to find chemical reactions that require less energy,
among other things. Meanwhile, it’s better to try capturing carbon dioxide from
smokestacks, where it’s much more concentrated, making the capture process
cheaper.

David
Keith,
director of the energy and environmental systems group at the University of
Calgary, argues in next week’s issue of Science that air capture (as capturing carbon dioxide from
the atmosphere is often called) could be cheaper than people think, and that it
may make more sense than other methods of offsetting carbon dioxide that are
being used today.

He’s
careful to point out that the economics are by no means certain at this point.
Indeed, he argues that what’s needed now is funding for some large-scale tests
to determine how much various processes really will cost. But his early
research, including preliminary work with a startup company, suggests that
costs for at least one part of the process–collecting carbon dioxide molecules
from the air–will be cheaper than once thought, he says. What’s more, such
systems could be located anywhere in the world, making it possible to choose a
location with low construction costs and easy access to geological structures for
storing the carbon dioxide, both of which would make the process cheaper.
Carbon dioxide capture from smokestacks, in contrast, must be done near
existing power plants, where construction costs and the cost of transporting
carbon dioxide to storage sites are higher.

Carbon
dioxide capture from smokestacks will probably still have the edge, he says.
But air capture may prove cheaper than other methods that are being funded now,
such as putting solar panels on roofs in dark regions (Germany, for example),
where payback times for the solar panels are very long.

Whether
or not it makes sense to fund demonstration projects or to focus on basic
research, air capture will likely play an important role in addressing climate
change in the coming century. Even with strict emissions cuts in place, the
carbon dioxide already in the atmosphere could cause serious problems. Air
capture could provide a way to actually reduce greenhouse-gas concentrations,
rather than merely stopping their growth.

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My reporting as MIT Technology Review’s senior editor for materials has taken me, among other places, to the oil-rich deserts of the Middle East and to China, where mountains are being carved away to build the looming cities.… More

Growing up, I lived for a time in the Philippines, where I knew people who lit their tiny homes with single lantern batteries or struggled to breathe through the dense diesel fumes of Manila, so I have a feel for the pressing need around the world for both cheap energy and clean energy.